The infantile winter diarrhea caused by human rotavirus is a severe diarrheic disease leading to pyrexia, vomiting, diarrhea, and dehydration, mainly in infants aged two or under. In Japan, infantile winter diarrhea is sometimes referred to as white diarrhea due to the light gray appearance of stools; however, it is clearly a human rotavirus infection. In the U.S., 3,500,000 children aged five or under suffering from diarrhea are annually diagnosed with a rotavirus infection; of these 55,000 are hospitalized, and 20 die. Worldwide, about 600,000 infants die annually from this disease, mainly in developing countries. Epidemiological surveys conducted in developed countries suggest that merely improving sanitary conditions cannot reduce the prevalence of rotavirus infection. The worldwide development of rotavirus vaccines has therefore been promoted as a countermeasure against such infections.
In both developed and developing countries, rhesus rotavirus tetravalent (RRV-TV) vaccine was found to be highly effective in preventing the severe diarrhea caused by rotavirus. In August 1998, the U.S. Food and Drug Administration approved RRV-TV vaccine as the first rotavirus vaccine in the world. However, the U.S. Centers for Disease Control and Prevention have since reported intussusception as a side effect of RRV-TV vaccine, and its administration has been discontinued (see Non-Patent Document 1, for example).
On the other hand, food constituents or food compositions that prevent rotavirus infection have been proposed, including immunoglobulins in colostrum and compositions thereof (see Patent Document 1, for example), bovine ic-casein (see Patent Document 2, for example), milk mucin (see Non-Patent Document 2, for example), buttermilk-derived polypeptides (see Non-Patent Document 3, for example), and such. However, these substances have yet to be assessed. Thus, the arrival of novel compositions against rotavirus infection that are effective in inhibiting rotavirus infections, and of food compositions that comprise the aforementioned compositions, is still anticipated.    [Non-Patent Document 1] Ishida Shinichi et al., “Rotavirus vaccine” The Journal of Pediatric Practice (Shonika Sinryo) Vol. 63, 2000, p. 1045-1049    [Non-Patent Document 2] Yolken, R. Y et al., “Human Milk Mucin Inhibits Rotavirus Replication and Prevents Experimental Gastroenteritis” J. Clin. Invest., Vol. 90, 1992, p. 1984-1991    [Non-Patent Document 3] Matsumoto Mitsuharu et al., “Buttermilk-derived anti-bovine rotavirus polypeptide” Nihon Chikusan Gakkaiho, Vol. 73, 2002, p. 49-56    [Patent Document 1] Japanese Patent Application Kokai Publication No. (JP-A) H3-72432 (unexamined, published Japanese patent application)    [Patent Document 2] Japanese Patent Kohyo Publication No. (JP-A) H10-505828 (unexamined Japanese national phase publication corresponding to a non-Japanese international publication)